1. Field of the Invention
The present invention is generally related to a mounting system for a marine propulsion device and, more particularly, to a mounting system that supports the drive at the transom with a compliant component, seals the transom to prevent water leakage, and provides vibratory and noise isolation.
2. Description of the Prior Art
Many different types of marine propulsion systems are well known to those skilled in the art. Typical marine propulsion devices are sterndrive systems, outboard motors, or inboard propulsion systems. Sterndrive systems typically include an internal combustion engine that is mounted for support within a marine vessel with a crankshaft of the internal combustion engine extending toward the stern. An outdrive member is attached to the transom of the boat and extends from the transom in an aft direction. The crankshaft of the engine is connected in torque transmitting relation with a driveshaft of the outdrive member. This connection between the crankshaft and the driveshaft extends through an opening formed through the transom of the marine vessel. Marine propulsion systems of this type are well known to those skilled in the art.
U.S. Pat. No. 3,865,068, which issued to Haasl on Feb. 11, 1975, discloses a sterndrive engine mount. A three point mounting system for the engine of a marine inboard-outboard sterndrive unit is disclosed. Bi-axially adjustable side mounts support the weight of the engine and an elastomeric sealing element around the driveshaft housing is radially expanded within a cylindrical passage through the transom to steady the engine in the region immediately adjacent the U-joint.
U.S. Pat. No. 4,925,414, which issued to Newman on May 15, 1990, discloses a marine propulsion system for isolating engine sound and vibration from the boat interior. It includes an engine mounted in the aft portion of the boat by resilient mounts. The engine is enclosed within a closed compartment for isolating engine sound, with one wall of the compartment defined by the boat transom. The resilient engine mount isolate the boat from the effects of engine vibration. A drive unit is rigidly mounted to the exterior of the boat transom. A drive mechanism is provided for transferring power from the engine crankshaft to the drive unit, and includes an apparatus for accommodating engine movements and isolating the drive unit from the effect of such movements.
U.S. Pat. No. 4,178,873, which issued to Bankstahl on Dec. 18, 1979, discloses an exhaust coupling assembly for a marine sterndrive. The apparatus includes an inboard engine having an exhaust passageway connected to an outboard drive unit having an exhaust passageway. A transom bracket assembly positioned between the engine and the drive unit permits vertical pivoting of the drive unit for steering and horizontal pivoting of the drive unit for trimming. The improvement includes a first exhaust pipe connected to the inboard engine and a second exhaust pipe connected to the drive unit. The first exhaust pipe extends outward through the transom of the boat and has an open end position centered on and adjacent the vertical pivot axis and below the vertical pivot axis. The second exhaust pipe extends toward and ends in alignment with the end position of the first exhaust pipe to form an interference which includes an opening between the pipe ends.
U.S. Pat. No. 4,362,514, which issued to Blanchard on Dec. 7, 1982, describes a high performance sterndrive unit. The marine propulsion device comprises a bracket adapted to be fixed to a boat transom and having an upper portion and a lower portion, a propulsion leg including a rotatably mounted propeller, a first ball joint universally connecting the propulsion leg and the lower bracket portion, a hydraulically cylinder-piston assembly having first and second ends, a pivot connecting the first end of the hydraulic cylinder-piston assembly to the propulsion leg about an axis which is generally horizontal when the bracket is boat mounted, a second ball joint universally connecting the second end of the hydraulic cylinder-piston assembly to the upper bracket portion, and a drive train adapted to be connected to a prime mover, extending through the bracket and the propulsion leg and drivingly connected to the propeller.
U.S. Pat. No. 4,371,348, which issued to Blanchard on Feb. 1, 1983, describes a mounting for a marine propulsion device located aft of a boat transom. It comprises a bracket adapted to be fixed relative to the transom of a boat and includes an opening extending generally horizontally when the bracket is boat mounted, a marine propulsion unit including a fixed assembly extending through the opening, fixed relative to the bracket, and including a power head located above the bracket and including an internal combustion engine. It also comprises an upper housing located below the bracket and fixed to the power head. The propulsion unit also includes a lower housing connected to the upper housing for pivotal movement therebetween about a tilt axis which is horizontal when the bracket is boat mounted, a gear case assembly connected to the lower housing for pivotal movement therebetween about a steering axis which is transverse to the tilt axis, a propeller rotatably carried by the gear case assembly, and a drive train connected to the propeller and the engine and extending through the gear case assembly and the lower and upper housings.
U.S. Pat. No. 5,944,569, which issued to Buzzi on Aug. 31, 1999, describes a simplified propelling system with drive integral to each other. The system supports a propeller shaft of adjustable inclination where the front end of the propeller-supporting shaft is carried by a hollow cylindrical body steadily fixed to the reversing gear box, which in turn is steadily fixed to the engine. The hollow cylindrical body comes out of the stem surface of the boat through a hole sealed by rubber rings which allow small angle adjustments to modify the inclination of the propeller-supporting shaft, further carried by an adjustable support placed outside the boat. The inclination of the propeller-supporting shaft is modified by raising or lowering a single assembly including the engine, the reversing gear box, the hollow cylindrical body and the propeller-supporting shaft.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Marine propulsion systems known to those skilled in the art are rigidly mounted to the transom of a marine vessel for at least one point of support. In a typical situation, where a sterndrive marine propulsion system is used, the system is supported by two or more engine supports that are attached to the engine and to the marine vessel to supply support for the engine. A third point of support is generally provided at the transom where the drive train of the sterndrive system passes through a hole in the transom. Usually, the engine is mounted to the inner surface of the transom with tube-like rubber isolators and an outdrive housing is rigidly mounted to an outer surface of the transom. These attachments of the engine and the outdrive to the transom provides support for both major members of the marine propulsion system and also provide sealing to prevent water from leaking through the transom proximate the hole formed to accommodate the torque transmitting shafts.
It would be significant beneficial if a means could be provided to adequately support the marine propulsion system while also isolating the propulsion system from the transom. This isolation would significantly reduce the transmission of vibration and noise, emanating from the engine and outdrive unit, to the boat.